Hi Hobbes, you are right, spirits are definitely still OP, especially since their damage and hardened armor ratings were not halved to reflect the reduced effects of armor.
The technomancer build was really aimed at giving the riggers (and technomancers) at heart; some ideas of how they can make a viable character that can scale from beginner missions to an advanced dragon hunting campaign. Most GMs and players would shelf a character who brought 18 drones with 18 attack dice each to their table on the first mission. But I can imagine it would be encouraged and entertaining for the final fight against a Magic 16 Blood Shaman and his guard of special forces, prof rating 8 grunts.
To answer the question as to how the technomancer would sustaining the complex forms for the drones. She/he uses the quality Concentration 3 to negate the sustaining modifiers for three complex forms.
Since drones would only ever need to use 3 skills in one round, the technomancer would not suffer from sustaining penalties.
While infiltrating: Manuevering, Clearsight, Sneaking.
While in combat: Evasion, targeting, and either maneuvering or clearsight.
The Remote control rig allows for up to 18 (rating level 6 rigs) drones to benefit from the same autosoft(s) using a single command from the technomancer.
The Nissan Samuria has a pilot and sensor rating of 3 and 2 allowing for 17 and 18 dice pools for combat attacks and defenses, which is not as high as a dedicated min/max shooter, but is comparable to a level 8 spirit.
The drones are glass cannons compared to spirits, but at least they are more robust than they were in 5E, as well as more robust than most player characters.
Either way, it is a fun idea, and a fun mechanic that I have enjoyed exploring.